@verrickt 谢谢你！能抽空看一下我回复楼上的吗？

@kaneg 你好！这个 setVisible 算不算异步呢？我看到 doc 里面有这一段话：
```
public void setVisible(boolean b)
Shows or hides this Dialog depending on the value of parameter b.
Overrides:
setVisible in class Window
Parameters:
b - if true, makes the Dialog visible, otherwise hides the Dialog. If the dialog and/or its owner are not yet displayable, both are made displayable. The dialog will be validated prior to being made visible. If false, hides the Dialog and then causes setVisible(true) to return if it is currently blocked.
Notes for modal dialogs.

setVisible(true): If the dialog is not already visible, this call will not return until the dialog is hidden by calling setVisible(false) or dispose.
setVisible(false): Hides the dialog and then returns on setVisible(true) if it is currently blocked.
It is OK to call this method from the event dispatching thread because the toolkit ensures that other events are not blocked while this method is blocked.
See Also:
Window.setVisible(boolean), Window.dispose(), Component.isDisplayable(), Component.validate(), isModal()
```

@momocraft 谢谢！请问一下 android 里面必须严格把类都放在 java 文件夹下面吗？

@chocotan 谢谢！我去查一下。

@chocotan 谢谢！

@BBCCBB 谢谢！这个确实可以。

@donyee 直接这样吗？
```java
Boolean ss;
ss = new DaoToUserInfo("porebook").queryUser(user);
```

@colincat 您好！我在学习 Java，不是说查询数据库这些操作最好要用多线程吗？如果是同步操作的话能否给个提示？